Search results for "thermoelectric material"

Engineering half-Heusler thermoelectric materials using Zintl chemistry

2016

In this Review, the structure, bonding and defects of half-Heusler compounds are explained in terms of the framework of Zintl (or valence-precise) chemistry. This deeper understanding of the structure and electronic properties of half-Heusler compounds should aid the design of improved thermoelectric materials.

Review on Polymers for Thermoelectric Applications.

2014

In this review, we report the state-of-the-art of polymers in thermoelectricity. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Since the prediction of the improvement of the figure of merit by means of electronic confinement in 1993, it has been improved by a factor of 3-4. In the mean time, organic materials, in particular intrinsically conducting polymers, had been considered as competitors of classical thermoelectrics, since their figure of merit has been improved several orders of magnitude in the last few years. We review here the evolution of the figure of merit or the power factor during the last years, and the best candidates…

Nanowires: A route to efficient thermoelectric devices

2019

Miniaturization of electronic devices aims at manufacturing ever smaller products, from mesoscopic to nanoscopic sizes. This trend is challenging because the increased levels of dissipated power demands a better understanding of heat transport in small volumes. A significant amount of the consumed energy in electronics is transformed into heat and dissipated to the environment. Thermoelectric materials offer the possibility to harness dissipated energy and make devices less energy-demanding. Heat-to-electricity conversion requires materials with a strongly suppressed thermal conductivity but still high electronic conduction. Nanowires can meet nicely these two requirements because enhanced …

Magnéli oxides as promising <em>n</em>-type thermoelectrics

2014

The discovery of a large thermopower in cobalt oxides in 1997 lead to a surge of interest in oxides for thermoelectric application. Whereas conversion efficiencies of p-type oxides can compete with non-oxide materials, n-type oxides show significantly lower thermoelectric performances. In this context so-called Magneli oxides have recently gained attention as promising n-type thermoelectrics. A combination of crystallographic shear and intrinsic disorder lead to relatively low thermal conductivities and metallic-like electrical conductivities in Magneli oxides. Current peak-zT values of 0.3 around 1100 K for titanium and tungsten Magneli oxides are encouraging for future research. Here, we …

Electrochemical Synthesis of Hybrid Layered Thermoelectric Materials Based on PEDOT/SnS Doped with Ag

2021

Thermoelectric properties of spark-plasma sintered nanoparticular FeSb2prepared via a solution chemistry approach

2013

Nanoparticular FeSb2 was prepared in solution from cyclopentadienyl iron(ii) dicarbonyl dimer [Fe(Cp(CO)2)]2 and antimony nanoparticles. Spark plasma sintering was used as consolidation method to maintain the particle size. The thermoelectric performance of FeSb2 is limited by its high thermal conductivity. In this work, the thermal conductivity was suppressed by nearly 80% compared to the bulk value by introducing grain boundary scattering of phonons on the nanoscale. The thermoelectric properties of the consolidated FeSb2 emphasize the possibility of altering thermal transport of promising thermoelectric compounds by phonon scattering by engineering the interfaces at the nanoscale.

Bond strength dependent superionic phase transformation in the solid solution series Cu2ZnGeSe4−xSx

2014

Recently, copper selenides have shown to be promising thermoelectric materials due to their possible superionic character resulting from mobile copper cations. Inspired by this recent development in the class of quaternary copper selenides we have focused on the structure-to-property relationships in the solid solution series Cu2ZnGeSe4−xSx. The material exhibits an insulator-to-metal transition at higher temperatures, with a transition temperature dependent on the sulfur content. However, the lattice parameters show linear thermal expansion at elevated temperatures only and therefore no indication of a structural phase transformation. 63Cu nuclear magnetic resonance shows clear indications…

Enhanced thermoelectric properties of the n-type Magnéli phase WO2.90: reduced thermal conductivity through microstructure engineering

2014

The thermoelectric properties of the Magneli phase WO2.90 were investigated, with special attention to how the thermoelectric performance can be altered by changing its microstructure. Spark plasma sintering (SPS) allowed the direct preparation of large amounts of consolidated material. Adding Ta2O5 to the reaction mixture lead to the formation of solid solutions W1−xTaxO2.90via a concurrent reaction between WO3 and Ta2O5 during the SPS treatment. In addition, micron-sized inclusions containing tungsten surrounded by WOx embedded in a WO2.90 matrix were formed, which act as additional scattering centers. As a result, the thermal conductivity of the Ta-containing samples was reduced by ≈30% …

Properties of spark plasma sintered nanostructured Zn1+xSb

2011

Engineering materials with specific physical properties has recently focused on the effect of nanoscopic inhomogeneities at the 10 nm scale. Such features are expected to scatter medium and long-wavelength phonons lowering thereby the thermal conductivity of the system without simultaneously decreasing the charge transport (phonon–glass electron–crystal concept). A new Zn1+xSb nanophase obtained by a wet chemical approach was densified by spark plasma sintering (SPS). Investigations on compounds subsumed as “Zn4Sb3” always suffer from its low thermal stability and the contamination of the nanoparticles with solvents and additives used in the synthesis. In order to gain insight into this com…

Peltier cells as temperature control elements: Experimental characterization and modeling

2014

Abstract The use of Peltier cells to realize compact and precise temperature controlled devices is under continuous extension in recent years. In order to support the design of temperature control systems, a simplified modeling of heat transfer dynamics for thermoelectric devices is presented. By following a macroscopic approach, the heat flux removed at the cold side of Peltier cell can be expressed as Q ˙ c = γ ( T c − T c eq ) , where γ is a coefficient dependent on the electric current, Tc and T c eq are the actual and steady state cold side temperature, respectively. On the other hand, a microscopic modeling approach was pursued via finite element analysis software packages. To validat…